1. Field of the Invention
The present invention relates to a lever switch required to have water proofing property and dust proofing property in an operating environment in particular such as a switch for detecting an opening/closed state of a power window of a vehicle.
2. Description of the Related Art
Japanese Patent Laid-Open No. 2000-331567 which discloses a waterproof lever switch has been applied by the applicant of the present invention.
This conventional switch has a structure in which a movable contact spring strip is disposed below a disk, from the perimeter of which a lever protrudes and a fixed contact is disposed below this movable contact spring strip. When an external force acts on the lever, a protrusion on the underside of the disk which rotates against a spring force presses the movable contact spring strip, the movable contact spring strip deflects and contacts the fixed contact to thereby turn on the switch. On the other hand, when the external force is released, the lever is restored to a neutral position through an elastic force of the spring, the movable contact spring strip separates from the fixed contact to thereby turn off the switch. A waterproof ring is inserted into a groove between the disk and a recess to provide water-proofing property.
In the conventional switch, the spring which biases the lever to the neutral position is disposed outside the disk and exposed without being covered. For this reason, this exposed spring may rust due to contact with water or the gap of the spring may be clogged with dust. This causes the spring to lose its elasticity, makes it difficult to restore the lever to the neutral position or the like, thus interfering with the operation of the lever and preventing the switch from functioning smoothly.
The present invention has been implemented in view of the above described problem and it is an object of the present invention to provide a lever switch which is perfectly and reliably preventable from water-intrusion or dust-intrusion through the casing of the switch, keeping smooth operation of a switch mechanism for a long period of time.